FIG. 1 is a perspective view of a conventional transistor outline (TO) can optical module package 100. The conventional TO-can package 100 comprises a base 101, with a heat sink (e.g. copper) block 111 and/or ceramic submount extending upwardly therefrom, and a plurality of electrical leads 102 extending therethrough. Typically, the leads 102 comprise two leads for driving a laser diode (LD) 103 and two leads for biasing a monitor photodiode (MPD) 104. The LD 103 and the MPD 104 are arranged on the surface the base 101 so that the mounted LD 103 points upwardly so that light emission is along the optical axis of the TO-can 100, and so that the MPD 104 receives a portion of the light emitted from the rear of the LD 103. In particular, LD 103 is mounted on the submount 111, e.g. with a hard solder (AuSn), with the MPD 104 disposed on the base 101 directly below the LD 103. The LD 103 and the MPD 104 are connected to the leads 102 by, for example, wire bonding.
The leads 102 are coaxially aligned via through-holes 113, which extend through the lower and upper surfaces of the base 101. The through-holes 113 are filled with a glass sealant 105, which is in a heated, fluid state during assembly, cools to a solid state, thereby fixing the leads 102 to the base 101 and hermetically sealing the through holes 113 at the same time. A cap 115, typically constructed from a material, e.g. Kovar, with a coefficient of thermal expansion matched to that of silica or glass, is mounted on the base 101 over top of the aforementioned electro-optical elements with some form of hermetical seal. Lensing 116 is typically provided along the optical axis of the TO-can 100 to control, e.g. focus, collimate, the light exiting the LD 103.
Unfortunately, TO-can packages do not scale well for high average power, and do not enable laser drivers to be positioned in close proximity to the laser. Accordingly, recent demand for LDs and multi-LD packages operating at high bit rates (>10 Gb/s) have necessitated modifications to the conventional TO can arrangement. For example, the number of leads must be increased to at least six, and the lengths of the leads extending from the TO can must be minimized. The amount of heat dissipated from the TO can must be increased. Moreover, it is highly beneficial for some of the electrical components to be disposed adjacent the laser, which is impossible with the current TO can structure.
An object of the present invention is to overcome the shortcomings of the prior art by providing a compact laser package with up to a plurality of laser diodes with minimal lead lengths utilizing a reflective ring to redirect light perpendicular to the substrate and out of the package.